1. Field of the Invention
An embodiment of the present invention relates to a photodetector.
2. Description of the Related Art
In recent years, technological development of a photodetector which inputs data with the use of a photodetector circuit (also referred to as an optical sensor) capable of generating data having a value corresponding to the illuminance of incident light, a photodetector which inputs data with the use of the photodetector circuit and outputs data in accordance with the input data, and the like have been advanced.
As an example of the photodetector, an image sensor can be given. As examples of the image sensor, a charge coupled device (CCD) image sensor, a complementary metal oxide semiconductor (CMOS) image sensor, and the like can be given (e.g., Patent Document 1).
In the photodetector disclosed in Patent Document 1, in one photodetector circuit, two optical data signals are generated and output to one optical conversion element and a difference data signal of the two optical signals is generated, so that adverse effects of noise can be reduced and data transmission rate can be increased by reducing the amount of data.